Prolong MacBook Battery Life by Limiting Max Charge Level
Given that I use my MacBook plugged in all the time to a dock/external display and I had previously on 30th August talked about having a USB-C data-passthrough-but-PD-shutoff-device to prolong the lifetime of the battery, I thought there might be something simpler I could try.
On searching on the internet I found a macOS tool called AlDente, which taps into the hidden SMC attribute called “BCLM” (Battery Charge Level Max), which tells the MacBook to stop charging once it hits a set level. By setting this attribute, you can set the max level at which to stop the battery from charging, mine is set to 70%, and it works exactly as expected. There’s also a CLI tool called “bclm” available that does exactly the same thing.
If you use your MacBook plugged in all the time, these tools are worth checking out as they will help to prolong battery lifespan and prevent the battery from getting overcharged and swollen. I have first hand experience of battery capacity drop and swelling due to overcharge (and the inconvenience of putting the laptop in service during the lockdown to get the batteries replaced) and would definitely recommend using them to ensure that it never happens again.